If you were to use those modes today it would be better to look at them as a concept rather than another mode. The modes we have today encompass pretty much everything, old modes and new. I'll try to explain it alittle easier, since I did rant alittle in the first post. Basically, to play something in a hypo-phrygain mode, you would play a locrian like you normally would but you would end whatever you played on the fourth note in the locrain mode.

Example: Playing a solo over a Bm7b5 chord, you would start on A and end the part on E. The harmony this would produce would be considered "hypo-phrygian". See it's more of a concept. With modern music you can do whatever, things aint as strict as in the pre-16th century. Hopefully that's alittle easier to understand. If not, don't worry about it. It's nothing big.